Book notes

Subliminal by Leonard Mlodinow

Read in December 2020

"If your mind's natural view of the world is skewed, it's skewed for a reason."

(Not a marketing book)

Our actions are hard to explain by pure intention and logic. Over the history, we didn't really understand the logic behind accurate guesses. Carl Jung and Sigmund Freud tried to explain the source of behavior is connected to subconscious. Today, Neuroscience enables the inspection of brain to interpret reactions more clearly. Neuroscience has been the quantum physics of psychology. It showed us the human mind is beyond what we thought.

  • Most of our actions are driven by unconscious mind that is evolved for survival.
  • Although it helps us to take shortcuts, our unconscious mind is also biased in many aspects.
  • We can tame our unconscious mind by understanding how it works, setting conscious goals, and acting mindfully.
  • Living a contradicting experience is a great way to eradicate bias.
  • Using Theory of Mind is a wonderful way to develop empathy and mindfulness.

Part 1: The Two-Tiered Brain

Most of the primitive creatures act "programmatically" to fulfill their basic instincts of survival and reproduction.

Humans (and mammals) have developed a part of brain that gives us the ability to make conscious decisions. Yet the pure logical conscious brain is a myth.

Our experiences shape the unconscious mind to direct our thinking towards certain ends. Mlodinow's mother for example, lost her mother at 16 to cancer, and her father, sister, and she were taken by the Nazis in Poland. She lost her sister and father, eventually escaped to the US to start a middle-low class life. Yet her traumatic early experiences made her think disastrously in such situations like Leonard skipping a routine phone call when he was studying away from home. His mom thought Leonard has died and his roommate didn't answer her calls to hide his death. In fact, Leonard was out for a date.

Freud and the subconscious

Sigmund Freud made great scientific progress to understand the brain connectivity and neural interactions.

Yet pursued in the clinical path and developed a theory for the subconscious based on his therapy. However, this method was inadequate since explaining the subconscious based on what patients tell him is scientifically unreliable (we will learn why in the upcoming chapters).

Freud suggested the subconscious is a defense mechanism that oppresses our desires to not take irrational actions.

Chapter 1: The New Unconscious

The new unconscious view the subconscious as a gift rather than a protection mechanism. Our subconscious helps us to direct our behavior based on the experiences and our interpretation of the materialistic world.

Some –hard to extract from what patients tell in therapy– examples of subconscious:

  • We want to feel important, this have a tendency to have a bias towards people who share similar traits. People tend to marry with others that have the same surname.
  • Popcorn-box combination experiment. Attendants decided how much to eat based on the taste of the popcorn and size of the boxes. Doubling the size of snack container increase consumption by 30-45 percent.
  • Fluency effect: we tend to like food, or find it more tasty based on the fonts used in the menu. It also shows the corporations with more readable names gained more interest during an IPO. So economy is not only about rational decisions based on self-interest.
  • The pepsi paradox: people prefer Coke, but Pepsi tastes better in a no-label experiment. Well, it's not a paradox. It's the perception of brand in our unconscious.

As a result, our unconscious minds are active, purposeful, and independent. They might be hidden, but their effects play a critical role in how the conscious minds perceive the world.

Chapter 2: Senses + Mind = Reality

TL;DR: Kant is right! There is reality that exists objectively, independent from us. Then there is another one build up by our senses and mind: the perceived reality.

The story of Charles Sanders Pierce, a pioneer in researching unconscious:

  • The stolen golden watch story (he guessed the burglar without no conscious evidence)
  • The weight perception experience (there is a threshold that we can sense in a set of weights perceived by our senses, and it's proportional)

He founded "the philosophical doctrine of pragmatism" and claimed that the philosophical ideas or theories should be viewed as instruments, not absolute truths.

An early metaphor for mental actions: There are two trains, unconscious and conscious which makes decisions. Now, it's viewed more like two railway systems with intersections.

Nevertheless, the unconscious part is more fundamental. It's developed far before than the conscious part. The unconscious takes up the 99% of the energy spent in brain. It's a bit funny, but playing chess vs watching television does not differ as drastically as running outside vs being a couch potato. Playing chess rather than watching TV increases the energy consumption only about 1%.

Processing visual data

One of the most important functions of the unconscious part is processing visual data. It occupies one-third of the brain capacity. It's developed to serve our survival instincts.

A patient with a damaged visual system that helps the conscious part can still distinguish images that trigger senses. He was able to differentiate happy and sad faces, where the results were not the same for geometric shapes. He was also able to walk without a cane, didn't step on to objects on the floor.

Faces play a special role in human behavior. Our facial expressions usually reflect how we perceive certain situations. That's why Helen of Troy said to have "a face that launched a thousand ships," not breasts.


"Blindsight" is the phenomena that claims the individuals can still respond to events without visually perceiving them in the conscious mind.

An artificial way to create blindsight is to show one eye a moving picture and the other one a static one that triggers an instinct, such as sexual desire.

We don't consciously perceive everything registered in our brain, so unconscious mind may notice something that conscious doesn't.

Another interesting concept that proves the wold we perceive is an artificial one is phonemic restoration. We fill in the blanks when something is missing to construct a meaning of what we perceive. It's done by the unconscious part and we totally believe. Sometimes they are biases towards the physical properties of the people we encounter such as race and ethnicity. We also match the concepts such as "orange" and "peel" to complete a sentence.

Chapter 3: Remembering and Forgetting

The case for memory distortion: false eyewitness identification, Jennifer Thompson, the victim who false identified her rapist during the line-up. She was relatively calm and trying to memorize the accuser during the incident. Yet she only remembered severe details to identify Ronald Cotton. But the actual suspect was actually Bobby Pole, another inmate Cotton met at the prison. The DNA test made the case accurate after 10 years.

James Dean and watergate. Dean was known as a man with a "tape recorder" memory. Yet his most recollections were false. They were either defend himself, or Raegan, who was actually tape recording everything.

Hugo Münsterberg and explorations of the new conscious

Munsterberg, another pioneering psychologist in the new conscious research, realized his memory distortion while filing a police report for a break-in to his house while they were away for a vacation. Most of his conclusions were based on what he heard from the policemen, and assumptions developed afterwards.

In fact, Munsterberg was very good in terms of memory. He gave over three thousand lectures without a single note. His studies on memory shown that the classical assumption of "our memories work like a rape recorder" was inaccurate.

He believed none of us can remember everything we are confronted. Instead, we remember certain blueprints, then fill the rest according to our belief systems and prior experience, sometimes to be self-serving. Additionally, we believe the memories we make up (confabulation).

Despite being a pioneer, one downside of Munsterberg was ignoring the unconscious mind. It's probably related with living in the same era as Freud, who where constructing a narrative that contradicts with Munsterberg's rational approach.

The story of the subconscious mind can be told in three words: there is none.

– Hugo Münsterberg

The man who remembered everything: Sheresevsky

Sheresevsky, a man lived in Russia, was able to remember everything. Yet he lacked interpretation. He didn't remember a person from her face. There were many faces that belonged to that person in his mind.

It shows that we evolved to trade perfect recall for the ability to handle and process information.

Two types of language structure

  • Surface: specific way the idea is suggested, with exact words and everything.
  • Deep: the gist of the idea.

We tend to make a gist out of our experiences based on the emotions. Then we fill up the missing parts when remembering them in the future. Sometimes we do that dramatically, and biased.

False memory experiments

Supporting to our power make ourselves believe in what we make up, there were a few good false memory placement experiments.

  • Hot air balloon ride: two of your childhood pics + one photoshopped.
  • Meeting with Bugs Bunny in Disneyland: he's a Warner Bros character.

After all, our memory is similar to sensors in the previous chapter. A big portion of it powered by the unconscious.

The lesson is to be humble, because our memories could be misplaced, and grateful both for the memories we can retain and the ability to not retain all of them.

Chapter 4: The Importance of Being Social

Social and emotional connections are beyond words, and can be understood through unconscious thought.

We value and amire kind, helpful behaviors. So being nice is it's own reward. It's also attracting other emotional beings.

Our tendency for social acceptance based on kindness starts to develop at early ages (~6 months). Babies that watch animations of "shapes with eyes" being rude (square brick tries to climb, triangle helps, circle pushes it down) or being neutral (circle is just a bystander) tend to reject playing with shapes that aren't helpful.

Another experiment made in 1950's in University of Minnesota. They gathered 2 x 30 female students. To the first group, they say there will be electroshocks it will hurt. To the second group, they said the electroshocks will just tickle. The group that expects painful experience waited in groups (66% - 33% in comparison) even though they had enough waiting rooms for every individual. So we seek help and unification with others when we are anxious.

Social pain is also physical

Tylenol (painkiller) experiment. People who took 2-tablets per day shown less affection from social problems compared to the people that took placebos. Lack of social connection constitutes a major risk factor for health.

Social intelligence and the "Theory of Mind"

Social intelligence is a result of our evolution. IT has been crucial to our survival. Human kind's ability to band together and organize preceded all the other creatures.

Social intelligence is not only corralated to IQ. It's influenced more by your desire and ability to understand what other people think and feel. It's called "Theory of Mind."

Most of our understanding in ToM comes from unconscious mind. There are levels of ToM.

  1. What I think
  2. What I think about what you think
  3. What I think about what you think about what I think
  4. What I think about what you think about what I think about what you think
  5. ...

Politicians and businessman are usually successful to think in 4th order.

Chain letters

It takes five steps to find two connected people by forwarding through connections. Same experiment done with both letters and email.

Mammals and social intelligence

Although we developed this complex brain and ToM (other mammals can do max 2nd order), there is also a big range of common behavior. Those behaviors are mostly on the unconscious side, and influenced by hormones.

Male Mammals -> reproductive success determined by competing with other males to mate with as many females as possible.

Female Mammals -> reproductive strategy is investing in production of relatively few offspring, and take care of them as they grow.

Oxytocin: love, trust. Vasopressin: commitment. Two hormones playing a key role in social interactions.

Social neuroscience

To investigate the effects of social connections, we have a new field called social neuroscience. Invention of fMRI contributed to many studies and made it clear that here's no way to understand human mind by focusing on rational or emotional extreme.

  • Cognitive psychology: mostly focuses on rational end.
  • Social psychology: mostly focused on emotional end.
  • Two + neuroscience => social neuroscience.

In the context of neuroscience, our brain consists of three main parts.

  1. Reptilian Brain: basic survival - fight or flight.
  2. Limbic System (Old Mammal Brain): unconscious social perception and reflective reptilian emotions.
  3. Neocortex (New Mammal Brain): homo sapiens! Evolved 200.000 years ago, effective around 50.000 years. Positioned on the frontal lobe, it's what makes us human. Conscious thought, planning and orchestrating in accordance of our goals happen here.

Part 2: The Social Unconscious

Chapter 5: Reading People

We unconsciously signal our expectations by our body language: gestures, facial expressions, posture, tone of voice.

Animals do that too, and they can also learn and understand human's intentions through the body language. Dogs evolved to understand humans the best.

Vasco de Gama Rats

Participants communicated more kindly with the "Vasco de Gama" rats (that are told to have abilities in mazes). In fact, they didn't. Yet those rats performed better than the other group (of stupid rats).

Similar things applied for teacher's behaviors against a class with "talented" and "normal" students. Brilliant (to be told) ones increased their IQ even more.

Non-linguistic communication in primates

Direct stare means treat, smile means "I won't attack you", or "please don't attack me, you're the best!"

Based on researches to rate human facial expressions in cross-demographies, it seems like our catalog of facial expressions are an inherent part of our being.


  • Physical dominance: voice, body, carrying a gun :D
  • Social dominance: expensive (or non-expensive) clothing, cars, watches

Visual dominance ratio. We automatically adjust the amount of time we're looking onto another person's eyes as a function of our relative social dominance. Percentage of the time you look while you are speaking against while you are listening is the visual dominance ratio. People tend to look more while speaking and less while listening when they're dominant.

Chapter 6: Judging People by Their Covers

Cowbird females get attracted to males by their voice. Even when it's coming from a stereo.

Humans also behave similarly in certain situations when voice is involved. We tend to trust love and relationship advices from women more, since they are known as "keepers." We obey orders from male voices more. We are not very biased on neutral topics. (I doubt that, but cool.)

Voice tone (deep-high) also effects humans when they are choosing their partners. People with physical dominance (long muscular male with hairy chest) sometimes adjust their voice tone to settle the conditions in social interactions (aww). Or the non-dominant individual does the opposite, especially if the case is competitive.

First presidential debate on air: Nixon vs. JFK (60' Elections)

Nixon had a knee problem and he was in the hospital. Yet he wanted to attend to the debate. He was looking pale and unhealthy. People in the TV insisted Nixon to wear a make up, but he said he'd only do it if Kennedy also does. Kennedy refused, so he followed.

It's said to be a determining factor (even the next generations that are neutral found Kennedy more "votable" just by watching the recording) on the race. Nixon's vice-president candidate said "That motherfucker just costed us the elections."

Another evidence for the importance of the look: people in Nixon's party who listened the debate through the radio didn't think it was too bad, until they re-watched the video recording.

Many other researches made in the US shown that "competent" looking candidates have enormous advantage when there's no strong ideology involved.

Some random findings:

  • Fast speakers create more trust they give a sense of competence.
  • Touching to forearm triggers some empathic feelings. Waiters got more tips and guys get more numbers on street when they did that.

Leonard says we can't turn off the "judging by look" ability. It'll always be there, as the other findings in the book.

Chapter 7: Sorting People and Things

Over the history, our species used categorization to increase their chance of survival.

If a bear ate uncle Johnny, then another bear can eat you tomorrow.

Unconscious mind transforms input by using categorization to speed up the reaction time. We are also using categorization to learn and remember things. Even our ability to read is empowered by categorization, so it's useful in many ways. However, it's also making us biased towards certain things.

When we categorize, we polarize.

Born of the Stereotype

Raise of the multi-culture societies and free will brought many different perspectives. Politicians, media, and businessman needed to address them somehow.

In order to leverage the power of mass media and managing the society, we came up with the concept of stereotypes. Then we started to generalize the behaviors –mostly negative because we also have a negativity bias.

Shoplifter reporting experiment. People reported "poor looking" shoplifters more than the "good looking" ones, and they also used more enthusiastic language when reporting the poor ones.

How to not to be a racist

We can fight with our unconscious in parallel to our conscious goals and values to tame biases. Still, as it's been said in Everything is Fucked, the most effective way to change a belief is to have a contradictory experience. That's the number one reason why forming multi-cultural, diverse, and inclusive groups are important.

It also seems like we're making progress (on polarizing :D), considering the disapproval rate of supremacist comments made by prolific people like Che Guevara (said "negro is lazy") and Abraham Lincoln (implied "white-black never be equal").

Chapter 8: In-groups and Out-groups

Robbels Cave Camp Experiment

11 x 2 eleven year old boys were called into a three week camp. They're almost indifferent in terms of race, socioeconomic and physical attributes.

They spent a week without being aware of the other group, banded and even created a name/flag/song for their group.

In the second week, teachers made them aware of the second group. They instantly wanted to compete with them in sports. Losing side burnt the flag ot he other team. The team with the burnt flag invaded and messed up the other team's room. In summary, there was a strong "US-VERSUS-THEM" feeling in the air.

(Rest of the story coming at the end)

As this study also shows, humans are not famous with their hospitality against groups they see different from themselves.

Sometimes we even make sacrifices to belong to a group. Most common pattern is the financial sacrifice. Mac-users vs PC-users, country club members, "senior" people who are OK to get promotion rather than salary increase.

In-group bias

In-group/out-group mindset makes us think that our in-group members are a lot more sophisticated. We tend to prefer them for social and business dealings.

Our self-identification also effects the performance. A study in Harvard on asian-american women students. They got a difficult math test, but divided into three groups that filled different questionnaires before the test.

  • Students who reminded their asian inheritance (correlates to being good at math) did the best.
  • Students who are asked to answer random cable TV questions (control group) did OK.
  • Students who reminded that they are women (seen as bad at math) did the worst.

Us versus them, but for real...

Sometimes the excluding behavior comes before the benefits of the tribe. Henri Tajfel experiment: you have limited amount of points to distribute between two people. The difference between distribution effects the total points, and you don't have to distribute all.

  • In-group (5 points – max) vs. In-group (5 points – max)
  • Out-group (1 points – min) vs. Out-group (1 points – min)
  • In-group (4 points – not max) vs. Out-group (1 points – min)

People were OK to give less points to in-group for the sake of minimizing out-group outcome.

What it takes to establish a kinsnip?

There's no minimal requirement to establish a tribe spirit. We can band against any common enemy very quickly.

The key to reduce in-group/out-group rivalry is to make them work together against ANOTHER COMMON ENEMY :D, or a natural disaster.

The two groups of the Robbels Cave Camp were united against solving the water outage and broken meal truck since it was a problem for both.

Mladinow says the same thing happened in 9.11, when he was living very close to the Empire States building.

It's sad but true.

At least there is a way.

Chapter 9: Feelings

William James, the man who lived the lifelong learner's dream... He studied various fields in very interesting universities, eventually settled down to get medical degree from Harvard. Yet he worked on psychology, as a student of Wundt.

His masterpiece (which he disowned at the time being and left the field for philosophy) The Principles of Psychology (took him 12 years to write) is still one of the most admired works in psychology.

James proposed the idea that psychology follow physiology. For example, we feel bad because we cry, not the other way around.

Emotions, in today's neo-Jamesian view, are like perceptions and memories. A big portion of the data comes from the unconscious mind, then the conscious part completes the rest with our preexisting beliefs and expectations. Adding the of interpretation of the current circumstances, we construct an emotion.

When you know where it's coming from...

Adrenaline experiments: subjects who are informed about the potential increase of their sexual desires where less interested in erotic films. (They were given injections then ran in treadmill)

If we somehow "know" the sources of our impulses, we are able to make more "mindful" decisions.


When we have no idea what led us to certain actions, we make up a narrative to justify our reasoning. The lack of agreement between the thinking brain and the feeling brain is the real issue.

Hiring experiment: subjects are evaluating a candidate based on academic success, a coffee-spilling incident, how attractive she is, and their possibility to meet her. Outside attendants are also try to guess why a subject would decide to hire the applicant.

Both the subjects and observers think that academic success was the biggest factor, but it had less effect than the other social norms.

As psychological theory suggested, the subjects had shown no greater interest into their reasoning than the outsiders had.

So we don't usually see ourselves no other than how the others see us.

Well, that's a bit bad. Perhaps the reason of the imposter syndrome.

To minimize the gap, we can broaden our perspectives and invest effort to know ourselves more deeply.

Yet sometimes it's futile to make a meaning out of everything.

If your mind's natural view of the world is skewed, it's skewed for a reason.

Chapter 10: Self

When we face with treats to feeling good about ourselves, our tendency to view reality through a distorting lens grows proportionally.

Many people think they are above-average in their professions.

Ironically, we tend to recognize that inflated self-assessment and overconfidence can be a problem–but only in others.

That's right, we even overestimate our ability to resist overestimating our abilities.

Two ways to get truth

  1. Scientist's Way: gather evidence, look for regularities, form theories explaining their observations, and test them.
  2. Lawyer's Way: being with a conclusion they want to convince others of and then seek evidence that supports it, while also attempting to discredit evidence that doesn't.

The human mind is evolved to be the both.

Motivated reasoning

Motivated reasoning helps us to believe in our own goodness and competence, to feel in control, and to generally see ourselves in an overly positive light.

Our brains show different physical behaviors when the subject is "us".

"You can’t connect the dots looking forward; you can only connect them looking backwards. So you have to trust that the dots will somehow connect in your future.

– Steve Jobs